Classifications

• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
  • G11B7/08—Disposition or mounting of heads or light sources relatively to record carriers
  • G11B7/09—Disposition or mounting of heads or light sources relatively to record carriers with provision for moving the light beam or focus plane for the purpose of maintaining alignment of the light beam relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following
• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B21/00—Head arrangements not specific to the method of recording or reproducing
  • G11B21/02—Driving or moving of heads
  • G11B21/10—Track finding or aligning by moving the head ; Provisions for maintaining alignment of the head relative to the track during transducing operation, i.e. track following
  • G11B21/106—Track finding or aligning by moving the head ; Provisions for maintaining alignment of the head relative to the track during transducing operation, i.e. track following on disks
• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
  • G11B7/08—Disposition or mounting of heads or light sources relatively to record carriers
  • G11B7/09—Disposition or mounting of heads or light sources relatively to record carriers with provision for moving the light beam or focus plane for the purpose of maintaining alignment of the light beam relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following
  • G11B7/0948—Disposition or mounting of heads or light sources relatively to record carriers with provision for moving the light beam or focus plane for the purpose of maintaining alignment of the light beam relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following specially adapted for detection and avoidance or compensation of imperfections on the carrier, e.g. dust, scratches, dropouts

Definitions

• the invention relates to a method for reading data from a rotating disk-shaped record carrier on which the data are recorded in spiral data tracks or in concentric circles by guiding a scanning device along the data tracks by means of a track control loop.
• a known player for disc-shaped rotating record carriers with spiral data tracks is the CD player.
• an optical scanning device scans the spiral data tracks of a so-called compact disc by means of a light beam.
• the light beam is focused by a focus control loop on the CD - the common abbreviation for compact disk.
• a track control loop guides the optical scanning device so that the light beam is always guided along the data tracks of the CD.
• the track control loop checks whether the light beam is still focused on the data track to be scanned. Usually it is offset radially inwards or outwards by a few data tracks. The track control loop calculates and he now generates a control signal so that the light beam jumps back onto the data track to be scanned.
• the invention solves this problem in that, during the ile reading of the data of the p-plate-shaped recording medium, the address of each point on the recording medium where the scanning device loses the data track is stored in a memory, that from the control signal, that the track control loop generates in order to lead the scanning device back onto the data track to be scanned, a modified control signal is calculated ⁇ and is also stored in the memory, that each time the data of the recording medium is read, the track control loop immediately reaches each of the stored points received modified control signal received from the memory in order to keep the scanning device as close as possible to the data track to be scanned.
• a second solution of the invention provides that the data of the recording medium are read for the first time in a first process step, that during the first reading of the data the address of each point of the recording medium gers, where the scanner loses the data track is stored in a memory that from the.
• Control signal which the track control loop generates in order to guide the scanning device back onto the data track to be scanned
• a first modified control signal is calculated and stored in the memory, so that in a second method step each stored point is approached by the scanning device, that as soon as each one is reached
• These points of the tracking control loop receive the stored associated first modified control signal from the memory in order to keep the scanning device as close as possible to the data track to be scanned, that a second from the control signal which the tracking control loop generates in order to guide the scanning device to the data track to be scanned modified control signal is calculated and stored in the memory, that the second method step is repeated until the direction of the track deviation or the sign of the modified control signal is reversed, that with each subsequent reading of the data of the recording medium either the modified control signal causing the reversal of the direction or the modified control signal determined immediately before the reversal of the direction is retained and is immediately output from the memory to the tracking control loop when each of the stored points is reached.
• Figure 1 shows a playback device for performing the method according to the invention
• Figure 2 shows a section of a compact plate with a dirty spot.
• FIG. 1 shows an example of a CD player which is suitable for carrying out the method according to the invention.
• a motor M1 rotates the compact disc CD, which is scanned by an optical scanning device AV by means of a light beam L.
• the light beam L is focused on the plate CD by means of an objective lens 0.
• the objective lens O With the aid of a drive F, the objective lens O can be moved a small distance radially inwards or outwards relative to the scanning device AV, as the double arrow indicates.
• the optical scanning device AV sits on a spindle SP which is driven by a motor M2.
• the optical scanning device AV can therefore be moved in the radial direction so that the light beam L can be guided along the data tracks on the disk CD.
• the spindle SP and the motor M2 are called coarse drives.
• a control circuit MP receives a tracking error signal TE from the optical scanning device AV;
• the control circuit MP generates a control signal TF for the fine drive and a control signal TG for the coarse drive from the tracking error ig ⁇ al TE.
• the fine and the coarse drive interact in such a way that the light beam L is guided along the data tracks of the disk CD.
• the optical scanning device AV gives the address AD of the respective scanned point on the disc CD to the rule MP It. If the light beam now reaches a contaminated location, for example, the control circuit MP no longer receives a tracking error signal TE. According to the method described in claim 1, the control circuit MP now causes the address of the last point recorded to be stored in the memory S.
• control circuit MP again receives a tracking error signal TE, it determines the deviation of the light beam L from the data track to be scanned and calculates a control signal from this track deviation in order to direct the light beam L back onto the data track to be scanned.
• a modified control signal is calculated from this control signal and stored in the memory S as belonging to the stored point. This process is repeated on each dirty or damaged location on the disc CD in order to store the addresses of all points and the associated modified control signals. All points of the disc CD, where the light beam loses the data track, and the modified control signal belonging to each point are therefore stored in the memory S.
• the control circuit MP determines this by comparison with the stored address. If the address supplied by the optical scanning device AV is the same as the address stored in the memory S, the control circuit MP fetches the modified control signal belonging to this point from the memory S and emits it to the tracking control circuit in order to quickly return the light beam to the one to be scanned Straighten data track.
• the modified control signals generated according to the method of claim 2 are also stored in the memory S.
• the addresses of the soiled or damaged areas and the associated first modified control signals are stored in the memory S after the first playing of the disc CD.
• the control circuit MP causes each of the stored points to be approached by the optical scanning device AV and the associated modified first control signal, which is stored in the memory S, to be output to the tracking control circuit.
• the track control loop now generates a control signal in order to direct the light beam L back onto the data track to be scanned.
• a second modified control signal is calculated from this control signal or from the track deviation and stored in memory S instead of the first modified control signal.
• This second method step is now repeated for each stored point until either the direction of the track deviation or the sign of the control signal is reversed. Either the modified control signal stored directly in the method step before the sign reversal or the modified control signal calculated during the sign reversal then remains in the memory S; it is no longer overwritten by a new modified control signal.
• the control circuit MP fetches the associated modified control signal from the memory S each time the light beam L arrives at one of the stored points, in order to direct the light beam back onto the data track to be scanned as shortly as possible behind the soiled or damaged point .
• FIG. 2 shows a section of a compact disc CD with five spiral data tracks A, B, C, D and E.
• a dust core SK covers part of the data tracks B and C.
• the disk CD is rotated in the direction of the arrow.
• the light beam L therefore moves in the direction of the arrow from left to right along the data track B.
• the light beam L runs uncontrollably over the data tracks behind point 1.
• it runs, for example, three data tracks radially inwards to data track E, where the track control loop catches it again and leads from point 2 on data track E.
• the Control circuit MP recognized that the light beam has moved three data tracks too far radially inwards. It therefore emits a control signal to the track control loop, which leads the light beam to point 4 on the data track B to be scanned.
• a modified control signal is calculated from this control signal and also stored in the memory S with the address of point 1.
• the modified control signal in the memory S is emitted to the track control loop when the disc is played when the light beam scans point 1 on the data track B. Therefore, the light beam is no longer up to data track E, but e.g. only deflected up to data track D, where it is captured by the track control loop in point 5.
• the control circuit MP has recognized that the light beam has to be displaced radially outwards by two data tracks in order to hit the data track B to be scanned again.
• the control circuit MP therefore generates a control signal so that the light beam moves from point 6 of data track D to point 7 of data track B to be scanned.
• the area of the unread data has shrunk because it now only extends on data track B from point 1 to point 7.
• the range of unsampled data is further restricted.
• the light beam moves from point 1 to point 2, further to point 3 and from there to point 4 on data track B.
• the address of point 1 and the associated first modified control signal are stored in the memory S, which. the same way as in the method according to claim 1 is calculated.
• point 1 is approached and the stored first modified control signal is delivered to the tracking control loop.
• the light beam L is now captured by the track control loop at point 5 on the data track D.
• the Rege Lscha Itu ⁇ g MP recognizes at point 6 that the light beam has to be displaced radially outwards by two data tracks in order to meet the data track B to be scanned again. It therefore generates a control signal which causes the light beam to be directed from point 6 on data track D to point 7 on data track B. From this control signal, a second modified control signal is calculated and stored in memory S.
• the light beam moves again to point 1; Because the track control loop now receives the second modified control signal stored in memory S, the light beam is already captured after data track C and directed to point 8 of data track C. At point 9 of data track C, control circuit MP has calculated and generated a control signal which directs the light beam to point 10 of data track B to be scanned. From this control signal, a third modified control signal is calculated and stored in the memory £.
• Point 1 is now approached a third time by light beam L.
• the track control loop receives the third modified control signal from the memory S.
• the third modified control signal now causes the light beam to be deflected radially outward to data track A.
• the track control loop catches the light beam L and directs it to point 11 of data track A.
• the control circuit MP after having recognized at point 11, that the light beam to offset a data track radially outward from the data track B to be scanned, a control signal to the track control loop so that the light beam is directed onto the data track B to be scanned.
• the third modified control signal remains in the memory S.
• control circuit MP When the light beam arrives at point 1 on data track B in game mode, control circuit MP outputs the optimal modified control signal belonging to point 1 in memory S to the track control loop. This is either the third or the fourth modified control signal.
• the light beam moves from point 1 to point 2, further to point 8 on data track C, then to point 9 on data track C and from there to point 10 the data track B to be scanned
• the light beam moves from point 2 to point 11 of data track A, further to point 12 of data track A and from there to point 13 on the data track B to be scanned, if the fourth modified control signal is stored in memory S as the optimal modified control signal.
• the amount of unscanned data is, as can be seen in FIG. 2, significantly reduced by the method according to the invention of claim 2.
• the extent to which the amount of unsampled data is reduced depends primarily on the size and shape of the soiled or damaged areas on the disk. The process explained using the example of the dust grain SK is carried out on all soiled or damaged areas of the plate.
• a first embodiment described in claim 3 provides that the speed of the disk is increased while the optimal modified control signal is determined step by step. This shortens the time required to carry out the method.
• the operator can either start or stop the method according to the invention.
• the third exemplary embodiment specified in claim 5 provides that the addresses of those points and the associated modified rules Isi gna le in the memory are automatically deleted when the light beam no longer loses the data track at these points. This can e.g. then be the case if the user has carefully cleaned the plate from dirt and fingerprints.
• a fourth exemplary embodiment, which is specified in claim 6, offers the operator the possibility of deleting the addresses and modified control signals in the memory himself at any time.
• the plates are marked; the addresses of the soiled or damaged areas as well as the associated modified control signals are stored for each marked plate. It is also possible, as the embodiment shown in claim 8 shows, to mark the plates of a magazine as belonging to the magazine. The addresses of the points and the associated modified control signals are stored sorted by plates and magazine.
• the places where the light beam loses the data track are mostly contaminated by dust or fingerprints, it makes sense to recommend the operator to clean the plate with an optical and / or acoustic signal if there are one or more points on the plate where the light beam leaves the data track to be scanned.
• an optical and / or acoustic signal can be generated.
• the text "Clean plate" may appear on a display device, a so-called display.
• the invention is suitable for playback devices which have a plate-shaped rotating recording medium without contact, e.g. scan with a light beam.
• Examples include CD players, video disc players, DRAW disc players and magneto-optical recording and playback devices.

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• Optical Recording Or Reproduction (AREA)
• Moving Of Head For Track Selection And Changing (AREA)

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Publications (1)

Family

ID=6424757

Family Applications (1)

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Citations (4)

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• 1991
  • 1991-02-09 DE DE4104017A patent/DE4104017A1/de not_active Withdrawn
• 1992
  • 1992-02-04 WO PCT/EP1992/000239 patent/WO1992014241A1/de active IP Right Grant
  • 1992-02-04 JP JP50351892A patent/JP3414731B2/ja not_active Expired - Fee Related
  • 1992-02-04 EP EP92903619A patent/EP0570410B1/de not_active Expired - Lifetime
  • 1992-02-04 DE DE59202741T patent/DE59202741D1/de not_active Expired - Fee Related
  • 1992-02-04 AT AT92903619T patent/ATE124560T1/de not_active IP Right Cessation
  • 1992-02-04 KR KR1019930702360A patent/KR100239108B1/ko not_active IP Right Cessation
• 1993
  • 1993-08-06 US US08/102,878 patent/US5450388A/en not_active Expired - Lifetime
• 1996
  • 1996-04-03 HK HK59196A patent/HK59196A/xx not_active IP Right Cessation

Patent Citations (4)

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